DENVER (CBS4) – Shoppers spent an estimated $52 billion over the weekend and the spending didn’t let up on Monday.

Experts say Cyber Monday, a busy online shopping day, was up at least 20 percent from a year ago. It’s an encouraging start to the shopping season, but it may not last.

The real challenge for retailers is keeping up the consumer’s enthusiasm, and this tough economy doesn’t make it easy. But consumers’ voracious appetites for great deals on Thanksgiving and Black Friday this year helped secure a place in the record books.

Darrin Duber-Smith is a marketing professor at Metropolitan State College of Denver. He has his pulse on the consumer.

“The average consumer has been hurting for a long time,” Duber-Smith said. “The average consumer doesn’t have as much money as they used to have … the average consumer isn’t seeing their income growing … the average consumer is kind of depressed right now.”

Digging deep into their budgets the average holiday shopper spent nearly $400 over the weekend, according to the National Retail Federation. That’s up from about $365 last year.

Retailers certainly generated sales, but it’s not clear how much of it means profit.

“It’s what we call cannibalization,” Duber-Smith said. “You’re robbing Peter to pay Paul to some degree. If you make a sale on Friday, it’s a sale you won’t be making a week later.”

If Duber-Smith is correct, sales should start to slip and flatten through the end of December.

But retailers know the shopping season is far from over and the last 2 weeks before Christmas are two very important weeks.

“I just don’t understand where the money is going to come from,” Duber-Smith said.

It depends on the deals. The deep discounts were a driving force to get people spending Black Friday weekend. It seems retailers will have to keep to an aggressive holiday promotion schedule to keep shoppers interested.

Retail experts say shoppers should expect to see more items on sale; specifically electronics and clothing.

It might just be a procrastinator’s Christmas because the last thing retailers want is to be stuck with a lot of leftover inventory come January.